Microstructural Aspects of High-Performance Cement-Based Materials

1994 ◽  
Vol 370 ◽  
Author(s):  
W. Jiang ◽  
D.M. Roy
Keyword(s):  
Mechanical Properties ◽  
Image Analysis ◽  
Radioactive Waste ◽  
Future Development ◽  
High Performance ◽  
Fiber Composites ◽  
Process Models ◽  
Strengthening Mechanisms ◽  
Computer Image Analysis ◽  
Cement Based Materials

AbstractThe goal of this research is to improve the physical properties, mechanical properties and durability of cement-based materials by controlling chemistry and processing to produce the desired microstructures and properties. An accompanying initiative is to establish the basic scientific understanding relating processing and microstructure with physical and mechanical behavior, for the future development of new, special purpose, high performance cement-based materials. The research involves both experimentation and theory elucidating fundamental strengthening mechanisms for materials such as warm-pressed, MDF, DSP, polymer, and fiber composites. SEM and computer image analysis were used. Of interest are creating process models that serve as a basis for real applications such as in the following areas: High-performance highway concrete, and the immobilization of radioactive waste.

scholarly journals Using Graphene Sulfonate Nanosheets to Improve the Properties of Siliceous Sacrificial Materials: An Experimental and Molecular Dynamics Study

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4824 ◽  
Author(s):  
Hongyan Chu ◽  
Zifei Wang ◽  
Yu Zhang ◽  
Fengjuan Wang ◽  
Siyi Ju ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
High Performance ◽  
Pore Diameter ◽  
Water Molecules ◽  
Scanning Calorimetry ◽  
Optimal Amount ◽  
Cement Based Materials ◽  
Decomposition Enthalpy ◽  
Sacrificial Materials

The fabrication of high-performance cement-based materials has benefited greatly from the extensive use of graphene and its derivatives. This paper studies the effects of graphene sulfonate nanosheets (GSNSs) on sacrificial cement paste and mortar (the tested materials) and other siliceous sacrificial materials, especially their ablation behaviors and mechanical properties. Decomposition temperatures and differential scanning calorimetry were used to examine how different contents of GSNSs determines the corresponding decomposition enthalpy of the tested materials and their ablation behaviors. Molecular dynamics was also used to clarify the mechanism how the GSNSs work in the CSH (calcium silicate hydrated)/GSNSs composite to increase the resistance to high temperature. The experimental results show that: (1) the contents of GSNSs at 0.03 wt.%, 0.1 wt.%, and 0.3 wt.% brought an increase of 10.97%, 22.21%, and 17.56%, respectively, in the flexural strength of siliceous sacrificial mortar, and an increase of 1.92%, 9.16%, and 6.70% in its compressive strength; (2) the porosity of siliceous sacrificial mortar was decreased by 5.04%, 9.91%, and 7.13%, respectively, and the threshold pore diameter of siliceous sacrificial mortar was decreased by 13.06%, 35.39%, and 24.02%, when the contents of GSNSs were 0.03 wt.%, 0.1 wt.%, and 0.3 wt.%, respectively; (3) a decline of 11.16%, 28.50%, and 61.01% was found in the ablation velocity of siliceous sacrificial mortar, when the contents of GSNSs were 0.03 wt.%, 0.1 wt.%, and 0.3 wt.%, respectively; (4) when considering the ablation velocities and mechanical properties of siliceous sacrificial materials, 0.1 wt.% GSNSs was considered to be the optimal amount; (5) the GSNSs contribute to the reinforced effect of GSNSs on CSH gel through the grab of dissociated calcium and water molecules, and the chemical reaction with silicate tetrahedron to produce S–O–Si bonds. These results are expected to promoting the development of new kinds of siliceous sacrificial materials that contain GSNSs.

scholarly journals Mechanical Properties of a Unidirectional Basalt-Fiber/Epoxy Composite

2020 ◽  
Vol 4 (3) ◽  
pp. 101 ◽  
Author(s):  
David Plappert ◽  
Georg C. Ganzenmüller ◽  
Michael May ◽  
Samuel Beisel
Keyword(s):  
Mechanical Properties ◽  
Carbon Fibers ◽  
High Performance ◽  
Glass Fibers ◽  
Basalt Fiber ◽  
Fiber Composites ◽  
Basalt Fibers ◽  
Strength And Stiffness ◽  
Better Than

High-performance composites based on basalt fibers are becoming increasingly available. However, in comparison to traditional composites containing glass or carbon fibers, their mechanical properties are currently less well known. In particular, this is the case for laminates consisting of unidirectional plies of continuous basalt fibers in an epoxy polymer matrix. Here, we report a full quasi-static characterization of the properties of such a material. To this end, we investigate tension, compression, and shear specimens, cut from quality autoclave-cured basalt composites. Our findings indicate that, in terms of strength and stiffness, unidirectional basalt fiber composites are comparable to, or better than epoxy composites made from E-glass fibers. At the same time, basalt fiber composites combine low manufacturing costs with good recycling properties and are therefore well suited to a number of engineering applications.

Investigation of the Common Modification Effect of Strontium and Antimony on the Structure in Case of Al-Si Alloy

2015 ◽  
Vol 812 ◽  
pp. 393-398
Author(s):  
Monika Tokár ◽  
György Fegyverneki ◽  
Valeria Mertinger
Keyword(s):  
Mechanical Properties ◽  
Image Analysis ◽  
Research Work ◽  
Computer Image Analysis ◽  
Cooling Conditions ◽  
Eutectic Si ◽  
The Common ◽  
The Given ◽  
Scanning Electron

In the course of our investigations, AlSi8Cu3 foundry alloy was alloyed in different strontium and antimony concentrations. The mechanical properties of structure developed during the given cooling conditions as well as the effect of strontium and antimony on the modification of eutectic Si were investigated by a computer image analysis and by using a scanning electron microscope. Samples with a wall-thickness of 8 mm cast in the course of the experiment-series were used for our investigations. A part of our long-term research work is described in our present paper.

Effect of Modified Phosphogypsum on the Mechanical Properties of Super Sulphate Cement

2012 ◽  
Vol 161 ◽  
pp. 264-268 ◽  
Author(s):  
Yu Xin Gao ◽  
Bao Ying Yu ◽  
Fen Lian Xu
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Compressive Strength ◽  
Chemical Composition ◽  
High Performance ◽  
High Strength ◽  
Strengthening Mechanisms ◽  
Particle Size Analyzer ◽  
Composition Analyzer ◽  
The Relationship

The effect of phosphogypsum (PG) modified on mechanical properties of super sulphate cement (SSC) was systematically studied in this paper. Then attentions and researches were focused on the relationship between specific surface (SSA) and the mechanical properties of SSC containing PG modified by calcining, floating, neutralizing with alkali. Strengthening mechanisms of SSC were further investigated and analyzed by laser particle size analyzer and chemical composition analyzer at last. Results showed that the high strength SSC with the compressive strength 35MPa at 7 days, over 60MPa at 28 days, and some even more than 70MPa at 56 days, could be successfully developed. This research can provide a key reference for the utilization of PG and development of high performance eco-SSC.

scholarly journals Experimental Study on Bond Stress between Ultra High Performance Concrete and Steel Reinforcement

2018 ◽  
Vol 3 (12) ◽  
pp. 1235 ◽  
Author(s):  
Ahad Amini Pishro ◽  
Xiong Feng
Keyword(s):  
Mechanical Properties ◽  
Shear Stress ◽  
High Performance ◽  
High Performance Concrete ◽  
Longitudinal Shear ◽  
Steel Reinforcement ◽  
Bond Stress ◽  
Axial Deformation ◽  
Ultra High Performance Concrete ◽  
Cement Based Materials

Due to axial deformations generally caused by flexure, shear stress will be generated across the interface between reinforcement and surrounding concrete. This longitudinal shear stress is called bond stress and coordinates deformation between concrete and reinforcement. With increasing a member's axial deformation, bond stress finally reaches its ultimate value, bond strength, after which deformation of reinforcement and surrounding concrete will be not coordinated any more. Studies have shown that addition of nanosilica into cement-based materials improves their mechanical properties. Considering the unique characteristics of nanosilica, it seems that this material can be used in ultra-high performance concrete. Therefore, further research is needed on how to use it in concrete mixes. Due to the importance of examining bond stress and the lack of exact equations for bond stress of ultra-high performance concrete and steel reinforcement, the present study aimed to assess the bond stress between concrete and steel reinforcement.

Three decades of auxetic polymers: a review

e-Polymers ◽  
2015 ◽  
Vol 15 (4) ◽  
pp. 205-215 ◽  
Author(s):  
Sukhwinder K. Bhullar
Keyword(s):  
Mechanical Properties ◽  
Future Development ◽  
Biomedical Engineering ◽  
High Performance ◽  
Chemical Resistance ◽  
Natural Sciences ◽  
Advanced Materials ◽  
Design And Technology ◽  
Auxetic Materials ◽  
Reduced Costs

AbstractDevelopments in design and technology in the engineering and medical fields necessitate the use of smart and high-performance materials to meet higher engineering specifications. The general requirements of such materials include a combination of high stiffness and strength with significant weight savings, resistance to corrosion, chemical resistance, low maintenance, and reduced costs. Over the last three decades, it has been demonstrated that auxetic materials offer a huge potential for the fields of engineering, natural sciences, and biomedical engineering, and for many other industries, including the aerospace and defense industries, through their unique deformation mechanism and measured enhancements in mechanical properties. To meet future engineering challenges, auxetic materials are increasingly being recognized as integral components of smart and advanced materials. Although materials with a negative Poisson’s ratio have been known since the early 1900s, they did not capture researchers’ attention until the late 1980s. Since 1991, these materials have been known as auxetic materials. Since then, their benefits and applications have been expanded to all major classes of materials such as metals, ceramics, polymers, and composites, and they are also now being used in engineering applications. The goal of this review was to present the development of auxetic polymers, which were first fabricated in the form of polyurethane foam approximately three decades ago and are now used in the fabrication of non-woven nano/micropolymeric structures. This review could provide useful information for the future development of auxetic polymers.

Surface Functionalization of Carbon Nanotubes and Compressive Strength of MWCNTs-OPC

2012 ◽  
Vol 511 ◽  
pp. 171-174 ◽  
Author(s):  
Fu Xia Wang ◽  
Yu Ying Wang
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Surface Functionalization ◽  
High Performance ◽  
Multiwall Carbon Nanotubes ◽  
Reinforcing Effect ◽  
Cement Based Materials ◽  
Highly Dispersed ◽  
Functionalization Of Carbon Nanotubes ◽  
Multiwall Carbon

Due to their remarkable mechanical properties, carbon nanotubes (CNTs) are considered to be one of the most promising reinforcing materials for the next generation of high-performance cementitious composites. However, the major problem is the highly attractive van der Waals forces between CNTs, which create coherent agglomerates that prove difficult to disperse in cement based materials and reduce the fluidity of the fresh mixture. In this study, the reinforcing effect of highly dispersed multiwall carbon nanotubes (MWCNTs) at ratios of 0.05, 0.1, 0.15， 0.2 and 0.25wt.% of cement has been investigated. The results show that small amount of effectively dispersed MWCNTs can significantly increase the strength of the cementitious

Macroprobe Mode for the Study of Segregation in Steels

1990 ◽  
Vol 48 (2) ◽  
pp. 260-261
Author(s):  
Auclair Gilles ◽  
Benoit Danièle
Keyword(s):  
Mechanical Properties ◽  
Spatial Distribution ◽  
High Performance ◽  
Volume Fraction ◽  
Sheet Steel ◽  
Acquisition Time ◽  
Chemical Information ◽  
X Ray ◽  
Accurate Quantitative Analysis ◽  
Optical Micrographs

During these last 10 years, high performance correction procedures have been developed for classical EPMA, and it is nowadays possible to obtain accurate quantitative analysis even for soft X-ray radiations. It is also possible to perform EPMA by adapting this accurate quantitative procedures to unusual applications such as the measurement of the segregation on wide areas in as-cast and sheet steel products.The main objection for analysis of segregation in steel by means of a line-scan mode is that it requires a very heavy sampling plan to make sure that the most significant points are analyzed. Moreover only local chemical information is obtained whereas mechanical properties are also dependant on the volume fraction and the spatial distribution of highly segregated zones. For these reasons we have chosen to systematically acquire X-ray calibrated mappings which give pictures similar to optical micrographs. Although mapping requires lengthy acquisition time there is a corresponding increase in the information given by image anlysis.

Recent developments in automated Transmission Electron MI

1989 ◽  
Vol 47 ◽  
pp. 46-47
Author(s):  
W.J. de Ruijter ◽  
P. Rez ◽  
David J. Smith
Keyword(s):  
Image Analysis ◽  
Computer Image ◽  
Lens Design ◽  
Computer Image Analysis ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Recent Developments ◽  
On Line ◽  
Routine Procedures ◽  
Near Future

There is growing interest in the on-line use of computers in high-resolution electron n which should reduce the demands on highly skilled operators and thereby extend the r of the technique. An on-line computer could obviously perform routine procedures hand, or else facilitate automation of various restoration, reconstruction and enhan These techniques are slow and cumbersome at present because of the need for cai micrographs and off-line processing. In low resolution microscopy (most biologic; primary incentive for automation and computer image analysis is to create a instrument, with standard programmed procedures. In HREM (materials researc computer image analysis should lead to better utilization of the microscope. Instru (improved lens design and higher accelerating voltages) have improved the interpretab the level of atomic dimensions (approximately 1.6 Å) and instrumental resolutior should become feasible in the near future.

Sign in / Sign up

Export Citation Format

Share Document